1. Field of the Invention
The present invention relates to a cellular phone set, and an incoming call notification method and incoming call notification control program used in the cellular phone set and, more particularly, to a cellular phone set suitably used in a place where the reception electric field strength of radio waves emitted from a radio base station is unstable, and an incoming call notification method and incoming call notification control program used in the cellular phone set.
2. Description of the Related Art
Upon reception of the radio wave emitted from a radio base station, a cellular phone set notifies the user of the incoming call by, for example, sounding a ringing tone or blinking an LED (Light-Emitting Diode) for incoming call notification. These incoming call notification means have been exclusively used to notify users of incoming calls but for no other purpose. Some cellular phone set is designed to have a function of setting different ringing tones for different callers so as to allow the user to identify a caller without seeing the display section. This function is aimed at saving the user from visually checking a caller. However, when the operation state of the cellular phone set has deteriorated (e.g., the battery voltage or reception electric field strength level has decreased), this function does not work to improve the deteriorated state.
As a cellular phone set that can solve this problem, for example, the cellular phone set disclosed in Japanese Unexamined Patent Publication No. 11-341120 (disclosed as “Mobile Radio Terminal”) has been proposed. According to the cellular phone set disclosed in this reference, information indicating a decrease in battery voltage or reception electric field strength is indicated by light emission from an LED. In addition, the battery residual amount is checked when the power is turned on or by user's operation. Furthermore, the reception electric field strength is indicated by light emission from the LED in accordance with user's operation or at intermittent intervals.
The following problems, however, arise in the cellular phone set disclosed in the above reference.
Information indicating a decrease in battery voltage or reception electric field strength is assumed to be indicated in a dark place, and hence is indicated by light emission from the LED alone. For this reason, only a visual effect can be obtained, and no satisfactory effect can be expected in a bright place. In addition, since the battery residual amount is checked when the power is turned on or by user's operation, the battery residual amount is not notified unless the user willing to check it. The notification of the battery residual amount at power-on produces little effect because the user does not usually turn off the power. Furthermore, since the reception electric field strength is indicated by light emission from the LED at intermittent intervals, a current is consumed even when the user need not know it. When the reception electric field strength is to be checked by user's operation, no notification is done unless the user is willing to check it.